Method and apparatus for receiving broadcasting data

ABSTRACT

A method and apparatus for receiving digital broadcasting data. The method for receiving digital broadcasting data includes: extracting location information of second service data which already received first service data refers to, from the first service data; by analyzing the location information, determining whether the second service data is in-band service data transmitted through an in-band channel, or out-of-band service data transmitted through an out-of-band channel; and if the second service data is transmitted through an out-of-band channel, determining the location information as the program number of the second service data.

BACKGROUND OF THE INVENTION

This application claims the priority of Korean Patent Application No.10-2004-0050428, filed on Jun. 30, 2004, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

1. Field of the Invention

The present invention relates to a method and apparatus for receivingdigital broadcasting data, and more particularly, to a method andapparatus for receiving digital broadcasting data which can be applieduniformly to in-band channels and out-of-band channels by defining a newnetwork service access point (NSAP) format.

2. Description of the Related Art

Digital broadcasting has enabled new application fields throughdigitalization of broadcasting contents. One of these new applicationfields is multimedia broadcasting.

Multimedia broadcasting is a new concept of broadcasting service whichis differentiated from the conventional audio and video broadcastingusing analog, or digital signals, and radios and TVs. While the servicesof the conventional broadcasting are limited to only simple transmissionof voice and images, multimedia broadcasting provides a variety of newservices unimagined by the conventional broadcasting, by transmittingdigital data through broadcasting channels.

For example, while KBS, a service provider, broadcasts a movie program,Troy, through a transmission line, KBS can make information on theproduction process and so on of Troy, be displayed to viewers. Then,when broadcasting the program, Troy, KBS transmits three types of data,including video data, audio data, and service data. A terminal receivesthe three types of data, then decodes the video and audio data by usinga decoder, and reproduces the data. The service data is processed by anapplication program of the terminal or an application program receivedthrough a transmission line, and then the processed result is outputthrough display apparatus to a user.

FIGS. 1A and 1B are diagrams showing a service information table (SIT)and a program mapping table (PMT), respectively.

The three types of data transmitted in digital broadcasting areprocessed in the form of files and data streams. When files aretransmitted, all files are divided into packets of a predeterminedlength. By the nature of broadcasting, packets are repeatedlytransmitted and a set of repeated packets is referred to as a carousel.Information on the relation between a packet and a program istransmitted through a separate process from the service provider to aterminal. This information is expressed, for example, as a serviceinformation table (SIT), a program mapping table (PMT), and so on. TheSIT maps source ID and program number. The source ID is an identifier ofa broadcasting provider, and a program number that is an identifier of abroadcast program (FIG. 1A), and the PMT maps a program number and apacket ID (FIG. 1B). The packet ID is an identifier for identifying apacket indicating video data, audio data, and service data included inone program. Based on the packet ID, a terminal obtains a packetcorresponding to a program that it requires, from a transmissionchannel.

Service data is generated by the service provider, and then broadcast toterminals. Service data can be an application program or applicationdata that is referred to by an application program. Hereinafter, inorder to distinguish these, the former will be referred to as a serviceprogram, and the latter as service reference data. Service data isobtained by a terminal from a transmission channel and is executed by aprocessor in the terminal. Generally, services programs are written byusing Java, HTML, MHEG, etc.

In a service program, there is a locator or a network service accesspoint (NSAP) including information on the location of reference datathat is referred to by each service program. The NSAP is defined byISO/IEC 8348 and is used as an address to identify a network end pointin an OSI networking model.

Meanwhile, digital broadcasting is performed through a transmissionchannel with a limited bandwidth. The transmission channel is dividedinto an in-band channel (IB) and an out-of-band channel (OOB) accordingto the size of a bandwidth of the transmission channel.

The in-band channel is a channel through which main data is broadcastaccording to predetermined broadcasting standards, and generally has avery large bandwidth, and transmits audio data, video data, and servicedata all together.

In broadcasting through the in-band channel, each broadcasting stationis assigned a source ID that is a unique identifier. In the out-of-bandchannel, broadcasting standards for data transmission are notdetermined, and the bandwidth is very narrow such that generally audioand video data are not transmitted and only service data is transmitted.In the out-of-band channel, a source ID is not used.

FIG. 1C is a flowchart of the operations performed by a method forreceiving data broadcast through an in-band channel.

In operation 110, a receiver obtains audio data, video data, and servicedata from a transmission line. If the service data is a service programand it is indicated that this service program should refer to anotherservice data, service reference data should also be received.

In operation 120, by analyzing an NSAP existing in the service programobtained in the operation 110, the receiver extracts the source ID ofservice reference data which the service program desires to refer to.

In operation 130, based on the service information table (SIT), thereceiver determines a program number (PN) corresponding to the sourceID. The SIT includes a table mapping a source ID and a program number(PN) and is transmitted from the broadcasting provider to receivers inadvance according to predetermined protocols.

In operation 140, the receiver determines a packet ID corresponding tothe program number based on the program mapping table (PMT).

In operation 150, by extracting packets having the packet ID among allpackets received by the receiver, based on the packet ID, the receiverselectively receives those packets.

Unlike the process of FIG. 1C, in broadcasting through an out-of-bandchannel, a source ID is not determined. Accordingly, based on a programnumber, the receiver extracts service reference data desired by the userfrom a transmission line. The program number is transmitted in advanceby the broadcasting provider to the receiver.

At present, as a digital broadcasting standard, OpenCable™ ApplicationPlatform (OCAP) is being prepared, and research activities for thisstandard currently being performed are to uniformly process service databoth in an in-band and an out-of-band channels.

FIG. 2 is a diagram of the structure of an NSAP according to theconventional OCAP.

Referring to FIG. 2, the conventional NSAP is formed with 20 bytes intotal. A private data field for a service program is assigned 10 bytes.

Among a variety of information items for a service program included inthe private data field, there is a 2-byte source ID. The source IDindicates location information on a network of service reference datawhich is transmitted. In digital broadcasting, location information ofservice reference data on a network is identified by using an NSAP andbased on this location information, the service reference data isobtained from a transmission line. The service reference data is datarequired for performing a service program broadcast, and is data or aprogram.

Which information should be recorded in the location information ofreference data varies depending on digital broadcasting standards. Inthe specifications of the OCAP or advanced common application platform(ACAP), a source ID is recorded in this service ID. A source ID is anidentifier for identifying a service provider broadcasting referencedata. At present, in the OCAP, the source ID is 2 bytes long, and eachservice provider of an in-band channel has a proper value.

Details of the OCAP are available in OpenCable™ Application PlatformSpecification as of Mar. 5, 2004, and in the specification, details ofthe NSAP can be found at OCAP specification 3.2.1 Definitions 18pLocator, 16.2.1.1. OCAP 1.0 Locator, and 16.2.1.5 Locators and contentreferencing. These contents are merged into the present invention.

However, the OCAP standard described above defines only the in-bandchannel and does not have any definitions on the out-of-band channel.Accordingly, the conventional NSAP shown in FIG. 2 cannot appropriatelyexpress location information of reference data incoming through anout-of-band channel.

SUMMARY OF THE INVENTION

The present invention provides a method for transmitting and receivingservice data in which a network service access point (NSAP) of a newformat that can be applied to both an in-band channel and an out-of-bandchannel is provided and by using this NSAP, the method for transmittingand receiving service data can be applied to both an in-band channel andan out-of-band channel.

According to an exemplary embodiment of the present invention, there isprovided a method for receiving digital broadcasting data including:extracting location information of second service data which alreadyreceived first service data refers to, from the first service data; byanalyzing the location information, determining whether the secondservice data is in-band service data transmitted through an in-bandchannel, or out-of-band service data transmitted through an out-of-bandchannel; and if the second service data is transmitted through anout-of-band channel, determining the location information as the programnumber of the second service data.

The location information may include a service type that is anidentifier for identifying whether the second service data is of anin-band or an out-of-band.

When the service type is one type, the location information may includea source identification (ID) of an in-band channel as the locationinformation of the second service data.

When the service type is another type, the location information mayinclude a program number of an out-of-band channel as the locationinformation of the second service data.

According to another aspect of an exemplary embodiment of the presentinvention, there is provided an apparatus for receiving digitalbroadcasting data including: a service processing unit which processesfirst service data already received by the receiving apparatus, and bydoing so, generates service output data; a PID determination unit whichdetermines the packet ID of second service data that is referred to bythe first service data, based on the location information in the firstservice data; and a filter unit which by filtering packets received bythe apparatus based on the packet ID, receives packets corresponding tothe second service data, wherein the location information includes anyone of a source ID and a program number of the second service dataaccording to whether the channel through which the second service datais transmitted is an in-band channel or an out-of-band channel.

The PID determination unit may include: an NSAP analysis unit which byanalyzing the NSAP, extracts the service type and the service ID; alocation information extraction unit which when the service type is onetype, determines the service ID as a source ID, and when the servicetype is another type, determines that the service ID indicates a programnumber, and by doing so, extracts any one of the source ID and theprogram number of the second service data, as location information ofthe second service data; an SIT mapping unit which by using apredetermined service information table (SIT), determines a programnumber mapped into the source ID; and a PMT mapping unit whichdetermines a packet ID corresponding to any one of a program numberextracted from the location information by using a predetermined programmapping table (PMT), and a program number extracted from the SIT mappingunit.

According to still another exemplary embodiment of the presentinvention, there is provided an apparatus for transmitting first servicedata when first service data of digital broadcasting refers to secondservice data transmitted to an out-of-band channel, the apparatusincluding: a first service generation unit which generates the programcode of the first service data including a network service access point(NSAP), and based on the program code of the first service data,generates a first program mapping table; a second service generationunit which generates the program code of the second service data, andbased on the program code of the second service data, generates a firstprogram mapping table including the program number of the second servicedata; an NSAP generation unit which by inserting the program number ofthe second service data from the second service program into an NSAP ofthe first service data, generates the NSAP of the first service data;and a transmission unit which transmits the first service data and thefirst service program mapping table.

According to yet still another exemplary embodiment of the presentinvention, there is provided a method for transmitting first servicedata when first service data of digital broadcasting refers to secondservice data transmitted to an out-of-band channel, the methodincluding: generating the program code of the first service dataincluding a network service access point (NSAP), and based on theprogram code of the first service data, generating a first programmapping table; generating the program code of the second service data,and based on the program code of the second service data, generating afirst program mapping table including the program number of the secondservice data; by inserting the program number of the second service datafrom the second service program into an NSAP of the first service data,generating the NSAP of the first service data; and transmitting thefirst service data and the first service program mapping table.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings in which:

FIGS. 1A and 1B are diagrams showing a service information table (SIT)and a program mapping table (PMT), respectively;

FIG. 1C is a flowchart of the operations performed by a method forreceiving data broadcast through an in-band channel;

FIG. 2 is a diagram of the structure of a network service access point(NSAP) according to the conventional OpenCable™ Application Platform(OCAP);

FIG. 3 is a diagram of the structure of an NSAP according to anexemplary embodiment of the present invention;

FIG. 4A is a diagram showing the structure of a source ID of FIG. 2defined in the OCAP specification;

FIG. 4B is a diagram showing a service ID of FIG. 2 newly definedaccording to an exemplary embodiment of the present invention;

FIG. 5 is a flowchart of a method for receiving digital broadcastingdata according to an exemplary embodiment of the present invention;

FIG. 6 is a diagram of a broadcast receiver according to an exemplaryembodiment of the present invention;

FIG. 7 is a diagram showing the internal structure of a packet ID (PID)determination unit; and

FIG. 8 is a diagram showing the internal structure of a transmitterwhich transmits service programs through an out-of-band channel by usingthe NSAP according to the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

Exemplary embodiments of the present invention will now be describedmore fully with reference to the accompanying drawings, in whichexemplary embodiments of the invention are shown.

Hereinafter, service data indicates additional data excludingaudio/video (AV) data among data transmitted through digitalbroadcasting.

Also, a service program indicates all types of application programincluding a program code formed to be executed in a receiver, as onetype of service data, and service reference data indicates pure dataexcluding service programs in service data. Accordingly, when firstservice data refers to second service data, the first service data canbe a service program, and the second service data can be pure data(hereinafter referred to as reference data) or another service program.

FIG. 3 is a diagram of the structure of an NSAP according to anexemplary embodiment of the present invention.

The NSAP according to the present invention has a 3-byte source ID area.

According to the NSAP of an exemplary embodiment of the presentinvention, the first 1 byte of the source ID area indicates a servicetype, and the remaining 2 byte area indicates a service ID.

Service type service_type indicates whether location informationincluded in a current program code is the location information ofreference data transmitted through an in-band channel or an out-of-bandchannel. For example, if service_type=00, then it indicates an in-bandservice, or else it indicates an out-of-band service.

Service ID service_ID indicates whether location information included inthe current program code is that of a service program transmittedthrough an in-band channel or an out-of-band channel. In case of thein-band channel, the service ID indicates a source ID of the serviceprogram, and in case of the out-of-band channel, the service IDindicates the program number of the service program transmitted throughan out-of-band channel.

A new NSAP format introduced in an exemplary embodiment of the presentinvention can express uniformly location information of programs ofin-band and out-of-band channels, by simply increasing the size of thesource ID area from 2 bytes to 3 bytes.

FIG. 4A is a diagram showing the structure of a service ID in an in-banddefined in the current OCAP specification, and FIG. 4B is a diagramshowing the structure of a service ID newly introduced in an exemplaryembodiment of the present invention.

FIG. 4A shows the structure of a source ID of FIG. 2 defined in the OCAPspecification.

When the first byte of the source ID is 00, the second and third bytesindicate a source ID. This service ID is only for indicating a source IDof an in-band channel.

When the first byte of the source ID is 01 or 02, it indicates locationinformation of abstract service by a manufacturer, a system operator(SO), or a multiple system operator (MSO). This location information canalso be used as location information of a service transmitted through anout-of-band channel. However, in relation to this location information,there is a problem that a program mapping table (PMT) cannot be obtainedand the location information is limited to abstract services. Inaddition, conversion into an NSAP is impossible.

Lastly, when the first byte of the service ID is 03-FF, nothing has beendefined yet. In the present embodiment of the present invention, a NSAPfor an out-of-band is defined by using this area.

FIG. 4B is a diagram showing a service ID of FIG. 2 newly definedaccording to an exemplary embodiment of the present invention.

In an exemplary embodiment of the present invention, a new service IDstructure that can use the OCAP specification of FIG. 4A without changeis proposed. That is, the structure of the service ID of FIG. 4A is usedwithout change and an area not defined yet (reserved area) in relationto the first byte of a service ID is used for generating an NSAP for anout-of-band.

In other words, in an exemplary embodiment of the present invention,when the first byte of a service ID is 03-FF, it is defined that thesecond and third bytes of the service ID indicate the program number ofa service incoming through an out-of-band channel. In relation to aservice incoming through an out-of-band channel, since no serviceinformation table (SIT) is formed for the service, there is no source IDin an NSAP. Accordingly, in order to execute the service incomingthrough an out-of-band channel, a terminal should directly obtain theprogram number, and therefore, as in the NSAP of FIGS. 3 and 4B,directly write a program number in the NSAP.

FIG. 5 is a flowchart of a method for receiving digital broadcastingdata according to an exemplary embodiment of the present invention.

In operation 510, a receiver obtains service data from a transmissionline. If the service data is a service program and it is indicated thatthis service program should refer to another service data, the servicereference data should also be received.

In operation 520, by analyzing an NSAP existing in the service programobtained in the operation 510, the receiver extracts a service type, andby examining whether or not the service type (the first byte) is 00,determines whether the corresponding service reference data istransmitted through an in-band channel or an out-of-band channel.

If the service type is an in-band, operation 530 is performed, or elseoperation 540 is performed.

In operation 530, the receiver extracts the second and third bytes inthe source ID area, as a source ID.

In operation 540, the receiver extracts the second and third bytes inthe source ID area, as a program number.

In operation 550, by using a service information table (SIT), thereceiver determines a program number (PN) corresponding to the source IDextracted in the operation 530. The SIT includes a table mapping asource ID and a program number (PN), and is transmitted in advance to areceiver by a broadcasting provider according to a predeterminedprotocol.

In operation 560, by using a program mapping table (PMT), the receiverdetermines a packet ID corresponding to the program number extracted inoperations 540 and 550.

In operation 570, by extracting packets with the determined packet IDamong all packets received by the receiver, the terminal selectivelyreceives the corresponding packets.

The reception method of FIG. 5 has an advantage that the method can beapplied to both service programs incoming through an in-band and anout-of-band. An example of service program A referring to service data Bwill now be explained. Service data B can be pure data or anotherservice program.

In the conventional method, when service program A refers to servicedata B transmitted through an out-of-band, location information ofservice data B transmitted to a receiver through an out-of-band is notdetermined by a source ID. Accordingly, it is impossible for serviceprogram A to record location information of service data B in an NSAP.However, in the reception method according to the present invention, anew NSAP format that can be applied uniformly to both an in-band and anout-of-band is defined and a new reception method according to this isdefined. By doing so, it is possible to record the location informationof service data B incoming through an out-of-band, in service program A.This can be briefed as shown in table 1: TABLE 1 Whether referring to ispossible Service program A Service data B Prior art Present invention IBIB Possible Possible OOB IB OOB Impossible Possible OOB

FIG. 6 is a diagram of a broadcast receiver according to an exemplaryembodiment of the present invention.

The broadcasting receiver according to an exemplary embodiment of thepresent invention includes a filter unit 610, a section data generationunit 620, a service data processing unit 630, an AV processing unit 640,an output unit 650, and a PID determination unit 660.

The filter unit 610 filters only packets indicating a program desired bya user among packets 600 received by the broadcasting receiver, based ona packet ID.

The section data generation unit 620 generates section data 622 and 644that is a minimum unit of carousel data, by combining the filteredpackets 612.

The service data processing unit 630 processes service data 622 in thesection data, and generates service output data 632.

The AV processing unit 640 processes audio data and video data 624 inthe section data, and generates AV output data 642.

The output unit 650 converts the service output data 632 and the AVoutput data 642 into data 652 that can be recognized by the user.

The PID determination unit 660 determines the packet ID 662 of a packetindicating another service data which is referred to by the service data632 that is received and stored by the service data processing unit 630.

FIG. 7 is a diagram showing the internal structure of the PIDdetermination unit 660.

The PID determination unit 660 receives service data 634 from theservice data processing unit 630, analyzes the service data, and bydoing so, determines the packet ID of another service data that isreferred to by the service data 634. For example, if service dataprocessed first by the service data processing unit 630 is serviceprogram A, and service program A refers to another service program B, byanalyzing an NSAP in service program A, the packet ID of service programB is determined.

The PID determination unit 660 includes an NSAP analysis unit 710, alocation information extraction unit 720, an SIT mapping unit 730, and aPMT mapping unit 740.

The NSAP analysis unit 710 receives service data 634 from the servicedata processing unit 630, analyzes the NSAP in the service data 634, andby doing so, extracts the service type 712 and the service ID 714. Theservice type 712 is the first byte of the source ID and the service ID714 is the second and third bytes of the source ID.

The location information extraction unit 720 generates the locationinformation of reference data 722 and 724 based on the service type 712and the service ID 714, and then transmits to the SIT mapping unit 730or the PMT mapping unit 740.

First, if the service type 712 indicates an in-band, the locationinformation extraction unit 720 determines the service ID 714 as thesource ID 722 of an in-band, and transmits the source ID 722 to the SITmapping unit 730. If the service type 712 indicates an out-of-band, thelocation information extraction unit 720 determines the service ID 714as the program number 724 of an out-of-band, and transmits the programnumber 724 to the PMT mapping unit 740.

The SIT mapping unit 730 determines a program number 732 mapped to thesource ID 722 by using a service information table (SIT). The SIT isprovided to the broadcasting receiver by a broadcasting provider usingan in-band channel.

The PMT mapping unit 740 determines the packet ID 662 mapped to theprogram number 732 and 724 by using a program mapping table (PMT). ThePMT is provided to the broadcasting receiver by a broadcasting providerusing an in-band channel or an out-of-band channel.

FIG. 8 is a diagram showing the internal structure of a transmitterwhich transmits service programs through an out-of-band channel by usingthe NSAP according to an exemplary embodiment of the present invention.

FIG. 8 shows a case where a first service program refers to a secondservice program transmitted through an out-of-band channel.

The transmitter according to an exemplary embodiment of the presentinvention includes a first service generation unit 810, a second servicegeneration unit 820, an NSAP generation unit 830, and a transmissionunit 840.

The first service generation unit 810 generates a first service program812, and generates a first program mapping table 814 written based onthe first service program code.

The second service generation unit 820 generates a second serviceprogram 822, and generates a second program mapping table 824 writtenbased on the second service program code.

Since the second service program 822 is transmitted through anout-of-band, the second program mapping table 824 includes a programnumber, not a source ID, as location information on the second serviceprogram 822.

When the first service program 812 refers to the second service program822, the second service generation unit 820 extracts the program numberof the second service program from the second program mapping table 824,and then transmits to the NSAP generation unit 830.

The NSAP generation unit 830 generates the second program numbertransmitted by the second service generation unit 820, in the format ofFIG. 3 in the NSAP of the first program, and by doing so, generates theNSAP 834 of the first program.

The transmission unit 840 receives the first service program 812, thefirst program mapping table 814, the second service program 822, and thesecond program mapping table 824 from the first and second servicegeneration units 810 and 820, converts these into transport streams andthen, transmits to the receiver.

Meanwhile, the method for receiving broadcasting data described abovecan be implemented as a computer program. Codes and code segmentsforming the program can be easily inferred by the programmers in thetechnology field of the present invention. Also, the program is storedin computer readable media, and read and executed by a computer toimplement the method for receiving digital broadcasting. The computerreadable media includes magnetic recording media, optical recordingmedia and carrier wave media.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims. Theexemplary embodiments should be considered in a descriptive sense onlyand not for purposes of limitation. Therefore, the scope of theinvention is defined not by the detailed description of the inventionbut by the appended claims, and all differences within the scope will beconstrued as being included in the present invention.

1. A method for receiving digital broadcasting data comprising:extracting location information of second service data which alreadyreceived first service data refers to, from the first service data;determining, by analyzing the location information, whether the secondservice data is one of in-band service data transmitted through anin-band channel and out-of-band service data transmitted through anout-of-band channel; and if the second service data is transmittedthrough the out-of-band channel, determining the location information asa program number of the second service data.
 2. The method of claim 1,wherein the location information includes a service type that is anidentifier for identifying whether the second service data is one of thein-band service data and the out-of-band service data.
 3. The method ofclaim 2, wherein when the service type is one particular type, thelocation information includes a source identification (ID) of thein-band channel as the location information of the second service data.4. The method of claim 2, wherein when the service type is oneparticular type, the location information includes a program number ofan out-of-band channel as the location information of the second servicedata.
 5. The method of claim 1, further comprising: when the secondservice data is transmitted through the in-band channel, determining thelocation information as a source ID of the second service data.
 6. Themethod of claim 5, further comprising: determining a program numbercorresponding to the source ID, based on a service information table(SIT) transmitted by a service provider of the in-band channel.
 7. Themethod of claim 1, further comprising: determining a packet IDcorresponding to the program number, based on a program mapping table(PMT) transmitted by a service provider of the out-of-band channel. 8.The method of claim 6, further comprising: determining a packet IDcorresponding to the program number, based on a program mapping table(PMT) transmitted by the service provider of the in-band channel.
 9. Themethod of claim 1, wherein the location information is identified usinga network service access point.
 10. An apparatus for receiving digitalbroadcasting data comprising: a service processing unit which processesfirst service data already received by the receiving apparatus, therebygenerating service output data; a packet ID (PID) determination unitwhich determines a packet ID of second service data that is referred toby the first service data, based on location information in the firstservice data; and a filter unit which, by filtering packets received bythe apparatus based on the packet ID, receives packets corresponding tothe second service data, wherein the location information includes oneof a source ID and a program number of the second service data accordingto whether the channel through which the second service data istransmitted is one of an in-band channel and an out-of-band channel. 11.The apparatus of claim 10, wherein the location information includes aservice type that is an identifier for identifying whether the secondservice data is one of in-band service data and out-of-band servicedata.
 12. The apparatus of claim 11, wherein when the service type isone particular type, the location information includes a source ID ofthe in-band channel as the location information of the second servicedata.
 13. The apparatus of claim 11, wherein when the service type isone particular type, the location information includes a program numberof the out-of-band channel as the location information of the secondservice data.
 14. The apparatus of claim 10, wherein the locationinformation comprises: a service type that is an identifier foridentifying whether the second service data is of one of the in-bandservice data and out-of-band service data; and a source ID when theservice type indicates the in-band service data, and a service IDindicating a program number when the service type indicates theout-of-band service data.
 15. The apparatus of claim 14, wherein thelocation information is identified using a network service access point(NSAP).
 16. The apparatus of claim 15, wherein the PID determinationunit comprises: an NSAP analysis unit which, by analyzing the NSAP,extracts the service type and the service ID; a location informationextraction unit which, if the service type is one particular type,determines the service ID as the source ID, and if the service type isanother type, determines that the service ID indicates a program number,thereby extracting one of the source ID and the program number of thesecond service data, as location information of the second service data;an SIT mapping unit which, by using a predetermined service informationtable (SIT), determines a program number mapped into the source ID; anda program mapping table (PMT) mapping unit which determines a packet IDcorresponding to one of a program number extracted from the locationinformation using a predetermined program mapping table (PMT), and aprogram number extracted from the SIT mapping unit.
 17. An apparatus fortransmitting first service data when first service data of digitalbroadcasting refers to second service data transmitted to an out-of-bandchannel, the apparatus comprising: a first service generation unit whichgenerates first program code of the first service data including anetwork service access point (NSAP), and based on the first program codeof the first service data, generates a first program mapping table; asecond service generation unit which generates second program code ofthe second service data, and based on the second program code of thesecond service data, generates the first program mapping table includingthe program number of the second service data; an NSAP generation unitwhich, by inserting the program number of the second service data fromthe second service program into an NSAP of the first service data,generates the NSAP of the first service data; and a transmission unitwhich transmits the first service data and the first service programmapping table.
 18. A method for transmitting first service data whenfirst service data of digital broadcasting refers to second service datatransmitted to an out-of-band channel, the method comprising: generatinga first program code of the first service data including a networkservice access point (NSAP), and based on the first program code of thefirst service data, generating a first program mapping table; generatinga second program code of the second service data, and based on theprogram code of the second service data, generating a first programmapping table including the second program number of the second servicedata; generating the NSAP of the first service data by inserting thesecond program number of the second service data from the second serviceprogram into the NSAP of the first service data; and transmitting thefirst service data and the first service program mapping table.
 19. Acomputer readable recording medium having embodied thereon a computerprogram for executing the method of claim 1.